The invention relates to a switching power supply unit that performs voltage conversion with one or more switching devices.
As some examples of a switching power supply unit, various DC-DC converters have been proposed and put into practical use (for example, refer to United States Patent Application Publication No. 2009/0196072 and U.S. Pat. No. 8,780,585). A DC-DC converter used for this purpose generally includes a switching circuit (an inverter circuit) including switching devices, a power conversion transformer (or a transformer element), and a rectifying smoothing circuit.